Adsorption–Catalysis Dual-Function Nitrogen-Doped Carbon/CoFe2O4 Composite for Efficient Tetracycline Removal

Efficient removal of tetracycline (TC) from antibiotic-contaminated wastewater remains a significant challenge. In this study, a nitrogen-doped carbon modified cobalt ferrite (C@CoFe2O4, CF) composite was synthesized via a one-step hydrothermal method, and its adsorption–catalysis dual-function performance was systematically evaluated. Structural characterization revealed that CoFe2O4 nanoparticles were locally encapsulated by an N-doped carbonaceous layer, providing a high specific surface area and abundant nitrogen-containing active sites. Under optimized conditions, the CF-3/PMS system achieved 93.44% TC removal within 45 min, while CF-3 exhibited a maximum adsorption capacity of 486.5 mg·g−1. Radical quenching experiments suggested that singlet oxygen (1O2) and superoxide radicals (O2•−) played major roles in TC oxidation, while sulfate radicals (SO4•−) and hydroxyl radicals (HO•) also contributed, indicating the coexistence of radical and non-radical oxidation pathways. TC adsorption was driven by surface complexation, π–π electron donor–acceptor interactions, and hydrogen bonding. The enhanced TC removal performance may arise from the cooperative contributions of N-containing carbon sites, accessible Co/Fe-containing regions, and interfacial electronic interactions, which promote TC enrichment and PMS-mediated oxidation. This work provides a promising strategy for designing bifunctional materials for antibiotic wastewater treatment.